(584u) Mechanistic Insights into Electrochemical C–N Coupling for Sustainable Organonitrogen Synthesis

Electrochemical synthesis of organonitrogen compounds from abundant C and N sources offers a sustainable route to valuable chemicals such as urea and cyclohexanone oxime. By leveraging CO₂ and NO₃⁻ species (or cyclohexanone and NO₂⁻) as feedstocks, this approach capitalizes on ambient-condition reactions that reduce reliance on fossil-based processes. Experimental trends indicate that product distributions shift significantly with pH and applied potential, reflecting the delicate balance between C–N coupling and competitive protonation pathways. To elucidate these complex reaction networks, we employ a suite of computational techniques including ab initio molecular dynamics (AIMD) with explicit solvation, constant potential DFT modeling with hybrid solvation, nudged elastic band (NEB) calculations, and enhanced sampling methods. These simulations identify key coupling pathways, *CO-*NOH, *CO-*NO, and *CO-*NO₂, and reveal that moderate potentials favor the formation of these coupling products, whereas highly negative biases promote undesired protonation steps.

Our integrated modeling framework pinpoints the rate-determining steps and energetic barriers that govern the electrochemical C–N bond formation across different systems. For instance, in the CO₂/NOₓ⁻ system, the formation of a *CO–NO₂ adduct is crucial, while in the cyclohexanone/NO₂⁻ pathway, controlled nitrite reduction enables selective oxime synthesis. The findings illustrate that both pH and electrode potential play pivotal roles in steering the reaction pathways, providing a molecular-level rationale for experimental observations. Ultimately, these insights offer a valuable foundation for the rational design of electrocatalysts that can precisely balance intermediate stabilization and reaction kinetics, thereby advancing the sustainable synthesis of a broad spectrum of C–N bond-containing products.